Đáp án:
Giải thích các bước giải:
`E=\frac{(sin\ \alpha+cos\ \alpha)^2-1}{cot\ \alpha-sin\ \alpha.cos\ \alpha}`
\(E=\dfrac{sin^2 \alpha+cos^2 \alpha+2sin\ \alpha.cos\ \alpha-1}{\dfrac{cos\ \alpha}{sin\ \alpha}-sin\ \alpha.cos\ \alpha}\)
\(E=\dfrac{1+2sin\ \alpha.cos\ \alpha-1}{cos\ \alpha.(\dfrac{1}{sin\ \alpha}-sin\ \alpha.)}\)
\(E=\dfrac{2sin\ \alpha.cos\ \alpha}{cos\ \alpha.\dfrac{1-sin^2\alpha}{sin\ \alpha}}\)
\(E=\dfrac{2sin\ \alpha.cos\ \alpha}{cos\ \alpha.\dfrac{cos^2\alpha}{sin\ \alpha}}\)
\(E=\dfrac{2sin\ \alpha.cos\ \alpha}{cos^3\ \alpha}\)
\(E=\dfrac{2sin\ \alpha.cos\ \alpha}{sin^2 \alpha}\)
\(E=2tan^2\alpha\)
